Keithley 213 voltage source driver: set_cmd producing error

[AngusRussell]

Hello, I am just getting started with QCoDes and I am trying to write a driver for a Keithley 213 voltage source. I have been following the examples in the documentation quite closely, however, I am having trouble with the set_cmd when adding a Parameter.

Here is the code for my driver so far:

from time import sleep, time

import numpy as np 
import matplotlib.pyplot as plt
import qcodes as qc

from qcodes.instrument import (
    Instrument,
    VisaInstrument,
    MultiParameter,
    InstrumentChannel,
    InstrumentModule,
)
from qcodes.utils import validators as vals

from qcodes.parameters import Parameter

class KeithleyChannel(InstrumentChannel):
    """
    Class to hold the four Keithley channels, i.e.
    port: 1, 2, 3, 4.
    """
    def __init__(self, parent: Instrument, name: str, channel: str) -> None:
        """
        Args: 
            parent: The Instrument instance to which the channel is to be attached.
            name: The `colloquial name of the channel
            channel: The name used by Keithley, i.e either 'P1', 'P2', 'P3' or 'P4'.
        """
        if channel not in ["P1", "P2", "P3", "P4"]:
            raise ValueError('Channel must be set to either port: "P1", "P2", "P3" or "P4"')
        
        super().__init__(parent, name)

        
        self.volt = Parameter(
            "volt",
            get_cmd = f"C0{channel}V?",
            get_parser = float,
            set_cmd = f"OUTPUT09;C0 {channel} A1 V{{}} X", # This string is not reaching the instrument as desired.
            label = "Voltage",
            unit = "V",
            instrument= self,
        )

        self.channel = channel

class Keithley213(VisaInstrument):
    """
        QCoDes driver for the Keithley 213 Quad voltage source.
    """ 
    def __init__(self, name: str, address: str, **kwargs) -> None:
        """
        Args:
            name: Name to use internally in QCoDes
            address: VISA resource address
        """
        super().__init__(name, address, **kwargs)

        for ch in ["P1", "P2", "P3", "P4"]:
            ch_name = f"{ch}"
            channel = KeithleyChannel(self, ch_name, ch_name)
            self.add_submodule(ch_name, channel)

        self.error_query = Parameter(
            "ErrorQuery",
            get_cmd = f"E?",
            instrument= self,
        )

        self.connect_message()

When I run

station = qc.Station()

keith = Keithley213('keithley', 'GPIB0::9::INSTR')

station.add_component(keith)

keith.P1.volt(3)

print(keith.error_query())

I get an error code E1 from the device which corresponds to an unrecognized command. The command I am trying to implement is straight from an example in the manual:

I have also tried multiple variations of this command, all with what should be correct syntax according to the manual. I think the {{}} is perhaps where I am running into issues as my other commands like the error_query work fine.

Does anyone know why the command is not parsing correctly?
Would a better option be to write my own parameter subclass?

Thanks :)

[jenshnielsen]

I would suggest that you set a higher logging level when communicating with the instrument to see if it is actually sending the command that you expect. See here for how that can be done https://qcodes.github.io/Qcodes/examples/logging/logging_example.html#Temporarily-elevating-the-logging-level

You can also verify that you can send the command using keith.write(command) and see if that works as expected

There should be no need to subclass for an example like this

[AngusRussell]

Thanks very much for your response. By enabling the higher level of logging I was able to uncover the issue. It was in fact the unspecified terminator argument in my VisaInstrument class that gave my commands a \r\n ending, but this being an old instrument it required an X ending.